fillers for planters

i ve seen a lot of peeps use polystyrene at base of a planter, is this to help drainage or to save money when filling the pot please
with my latest planters i started with crocks [broken clay pots], then compost plus water retaining gel to 2/3 then compost to top..... this is standard for annuals
for permanent plants/shrubs i mixed compost and john innes no3, also gel for first 2/3, and finished off with a layer of shingle to keep plants cool and to match the ground cover

[ 24. March 2006, 05:14 AM: Message edited by: Lady Gardener ]

 

If I've got a number of smallish plants in a big container, I use polystyrene just as a filler, but also helps keep down the weight as a bonus.

Only used JI no 3 for top dressing so far, and I also mulch over containers with shingle.

 

TLG - I use polystyrene - yes, for cheapness in drainage, but also for not adding any more weight to a potentially extremely heavy pot!! :D

 

i use old newspapers scrunched up in a ball and packed in.under my front window i sow night scented stock in a big troff for summer nights, that sits on some bricks.good drainage and saves on compost.i use it in large plastic tubs for marigolds in my back yard cos ive got no garden there as such to plant in.

 

I dont find you need drainage material in a summer container, the main problem there is getting enough water in.
For permanent containers that are going to stand out all winter I tend to mix a largeish amount of sharp grit with the compost, so that the whole thing drains well. Unless its massive I dont like to take up root space.
On the subject of night scented stock elaine, have you tried a plant called 'zaluzianskya capensis' its quite an interesting flower as well as night scented.

 

Hi pete2255, I have just received some zaluzianskya capensis seeds from Chilterns, as I don't like the smell of stock . Were you pleased with it?

 

Yes its quite a good little plant I think, its tidy and makes a compact little plant that flowers for quite a while, then when its finished, you can cut it back and it'll flower again.
Also you can take cuttings and overwinter them frost free, for early flowers the following year.
The evening scent as far as I'm concerned is a bit like vanilla, but then my nose is not the same as others.

 

thanks pete, i`ve written it down cos i`ll never remember otherwise.vanilla is my FAVOURITE.

 

Thanks! I'll plant some if it ever stops raining....

 

If you are going to reduce your root space with polystyrene, your plant will suffer in the long run as you will loose valuable moisture retention and food supply. You may as well use a smaller pot. It is the same as using poor quality compost, cheap but, the plants will suffer.

 

I have seen extensive discussions on an American forum on pot requirements. What I learnt is that you need to get oxygen to the roots, and so you do need a little bit of gravel or polystyrene at the bottom, or a lot of drainage holes to allow the oxygen to get into the compost.

Other than that Hans is quite right, you are making your pot smaller, and your plant will suffer. Surprisingly, a lot of gravel or similar at the bottom also make the drainage worse. The drainage of small pots is always worse than for big pots (it is governed by physics and the wicking action).

Another thing that was new to me is a major reason for changing the compost after one or two years is not lack of nutrition (you can always feed it) but that the compost breaks down with time. And as it gets finer the wicking action increases and the drainage gets worse.

 

That reminds me - you're advised to scrape off the top inch or so of compost every year, and replace that, if you have the sort of pot where it's not practical to re-pot, e.g. a customer who had an acer in a large pot, and it had been there for many a year. I learn a lot from my elderly customers - part of the fun of the job! :D

 

This thread on a US forum also suggested that you should not use peat for long term potted plants, because of the problem of the peat breaking down and the drainage getting progressively worse. They were advocating crushed rock (sand?)and other items that did not seem to be available in the UK. However it would seem sensible to use more loam/garden soil, which I imagine is more stable over time.

 

I think thats right Peter, I tend only to use peat based compost on short term pots ie. one season. Anything longer and I use John Innes, I buy the no 3 and add some peat, or organic matter of some kind, or grit, depending on what the particular plant likes.